1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
18 Revision 1.14 1999/11/02 17:15:54 fca
19 Correct ansi scoping not accepted by HP compilers
21 Revision 1.13 1999/11/02 17:14:51 fca
22 Correct ansi scoping not accepted by HP compilers
24 Revision 1.12 1999/11/02 16:35:56 fca
25 New version of TRD introduced
27 Revision 1.11 1999/11/01 20:41:51 fca
28 Added protections against using the wrong version of FRAME
30 Revision 1.10 1999/09/29 09:24:35 fca
31 Introduction of the Copyright and cvs Log
35 ///////////////////////////////////////////////////////////////////////////////
37 // Transition Radiation Detector version 2 -- slow simulator //
41 <img src="picts/AliTRDfullClass.gif">
46 ///////////////////////////////////////////////////////////////////////////////
53 #include "AliTRDmatrix.h"
60 //_____________________________________________________________________________
61 AliTRDv1::AliTRDv1(const char *name, const char *title)
65 // Standard constructor for Transition Radiation Detector version 2
95 SetBufferSize(128000);
99 //_____________________________________________________________________________
100 AliTRDv1::~AliTRDv1()
103 if (fDeltaE) delete fDeltaE;
107 //_____________________________________________________________________________
108 void AliTRDv1::CreateGeometry()
111 // Create the GEANT geometry for the Transition Radiation Detector - Version 2
112 // This version covers the full azimuth.
115 // Check that FRAME is there otherwise we have no place where to put the TRD
116 AliModule* FRAME = gAlice->GetModule("FRAME");
119 // Define the chambers
120 AliTRD::CreateGeometry();
124 //_____________________________________________________________________________
125 void AliTRDv1::CreateMaterials()
128 // Create materials for the Transition Radiation Detector version 2
131 AliTRD::CreateMaterials();
135 //_____________________________________________________________________________
136 void AliTRDv1::Diffusion(Float_t driftlength, Float_t *xyz)
139 // Applies the diffusion smearing to the position of a single electron
142 if ((driftlength > 0) &&
143 (driftlength < kDrThick)) {
144 Float_t driftSqrt = TMath::Sqrt(driftlength);
145 Float_t sigmaT = driftSqrt * fDiffusionT;
146 Float_t sigmaL = driftSqrt * fDiffusionL;
147 xyz[0] = gRandom->Gaus(xyz[0], sigmaL);
148 xyz[1] = gRandom->Gaus(xyz[1], sigmaT);
149 xyz[2] = gRandom->Gaus(xyz[2], sigmaT);
159 //_____________________________________________________________________________
160 void AliTRDv1::Hits2Digits()
163 // Creates TRD digits from hits. This procedure includes the following:
165 // - Gas gain including fluctuations
166 // - Pad-response (simple Gaussian approximation)
167 // - Electronics noise
168 // - Electronics gain
171 // The corresponding parameter can be adjusted via the various Set-functions.
172 // If these parameters are not explicitly set, default values are used (see
174 // To produce digits from a root-file with TRD-hits use the
175 // slowDigitsCreate.C macro.
178 printf("AliTRDv1::Hits2Digits -- Start creating digits\n");
180 ///////////////////////////////////////////////////////////////
182 ///////////////////////////////////////////////////////////////
184 // Converts number of electrons to fC
185 const Float_t el2fC = 1.602E-19 * 1.0E15;
187 ///////////////////////////////////////////////////////////////
195 // Get the pointer to the hit tree
196 TTree *HitTree = gAlice->TreeH();
197 // Get the pointer to the digits tree
198 TTree *DigitsTree = gAlice->TreeD();
200 // Get the number of entries in the hit tree
201 // (Number of primary particles creating a hit somewhere)
202 Int_t nTrack = (Int_t) HitTree->GetEntries();
205 Int_t chamEnd = kNcham;
206 if (fSensChamber) chamEnd = chamBeg = fSensChamber;
208 Int_t planEnd = kNplan;
209 if (fSensPlane) planEnd = planBeg = fSensPlane;
211 Int_t sectEnd = kNsect;
212 if (fSensSector) sectEnd = sectBeg = fSensSector;
214 // Loop through all the chambers
215 for (Int_t icham = chamBeg; icham < chamEnd; icham++) {
216 for (Int_t iplan = planBeg; iplan < planEnd; iplan++) {
217 for (Int_t isect = sectBeg; isect < sectEnd; isect++) {
221 printf("AliTRDv1::Hits2Digits -- Digitizing chamber %d, plane %d, sector %d\n"
222 ,icham+1,iplan+1,isect+1);
224 // Create a detector matrix to keep the signal and track numbers
225 AliTRDmatrix *matrix = new AliTRDmatrix(fRowMax[iplan][icham][isect]
228 ,isect+1,icham+1,iplan+1);
230 // Loop through all entries in the tree
231 for (Int_t iTrack = 0; iTrack < nTrack; iTrack++) {
234 nBytes += HitTree->GetEvent(iTrack);
236 // Get the number of hits in the TRD created by this particle
237 Int_t nHit = fHits->GetEntriesFast();
239 // Loop through the TRD hits
240 for (Int_t iHit = 0; iHit < nHit; iHit++) {
242 if (!(TRDhit = (AliTRDhit *) fHits->UncheckedAt(iHit)))
245 Float_t x = TRDhit->fX;
246 Float_t y = TRDhit->fY;
247 Float_t z = TRDhit->fZ;
248 Float_t q = TRDhit->fQ;
249 Int_t track = TRDhit->fTrack;
250 Int_t plane = TRDhit->fPlane;
251 Int_t sector = TRDhit->fSector;
252 Int_t chamber = TRDhit->fChamber;
254 if ((sector != isect+1) ||
255 (plane != iplan+1) ||
256 (chamber != icham+1))
259 // Rotate the sectors on top of each other
260 Float_t phi = 2.0 * kPI / (Float_t) kNsect
261 * ((Float_t) sector - 0.5);
262 Float_t xRot = -x * TMath::Cos(phi) + y * TMath::Sin(phi);
263 Float_t yRot = x * TMath::Sin(phi) + y * TMath::Cos(phi);
266 // The hit position in pad coordinates (center pad)
267 // The pad row (z-direction)
268 Int_t rowH = (Int_t) ((zRot - fRow0[iplan][icham][isect]) / fRowPadSize);
269 // The pad column (rphi-direction)
270 Int_t colH = (Int_t) ((yRot - fCol0[iplan] ) / fColPadSize);
272 Int_t timeH = (Int_t) ((xRot - fTime0[iplan] ) / fTimeBinSize);
274 // Array to sum up the signal in a box surrounding the
276 const Int_t timeBox = 5;
277 const Int_t colBox = 7;
278 const Int_t rowBox = 5;
279 Float_t signalSum[rowBox][colBox][timeBox];
280 for (iRow = 0; iRow < rowBox; iRow++ ) {
281 for (Int_t iCol = 0; iCol < colBox; iCol++ ) {
282 for (Int_t iTime = 0; iTime < timeBox; iTime++) {
283 signalSum[iRow][iCol][iTime] = 0;
288 // Loop over all electrons of this hit
289 Int_t nEl = (Int_t) q;
290 for (Int_t iEl = 0; iEl < nEl; iEl++) {
292 // Apply the diffusion smearing
293 Float_t driftlength = xRot - fTime0[iplan];
298 Diffusion(driftlength,xyz);
300 // At this point absorption effects that depend on the
301 // driftlength could be taken into account.
303 // The electron position and the distance to the hit position
305 // The pad row (z-direction)
306 Int_t rowE = (Int_t) ((xyz[2] - fRow0[iplan][icham][isect]) / fRowPadSize);
307 Int_t rowD = rowH - rowE;
308 // The pad column (rphi-direction)
309 Int_t colE = (Int_t) ((xyz[1] - fCol0[iplan] ) / fColPadSize);
310 Int_t colD = colH - colE;
312 Int_t timeE = (Int_t) ((xyz[0] - fTime0[iplan] ) / fTimeBinSize);
313 Int_t timeD = timeH - timeE;
315 // Apply the gas gain including fluctuations
316 Int_t signal = (Int_t) (-fGasGain * TMath::Log(gRandom->Rndm()));
318 // The distance of the electron to the center of the pad
319 // in units of pad width
320 Float_t dist = (xyz[1] - fCol0[iplan] - (colE + 0.5) * fColPadSize)
323 // Sum up the signal in the different pixels
324 // and apply the pad response
325 Int_t rowIdx = rowD + (Int_t) ( rowBox / 2);
326 Int_t colIdx = colD + (Int_t) ( colBox / 2);
327 Int_t timeIdx = timeD + (Int_t) (timeBox / 2);
328 signalSum[rowIdx][colIdx-1][timeIdx] += PadResponse(dist-1.) * signal;
329 signalSum[rowIdx][colIdx ][timeIdx] += PadResponse(dist ) * signal;
330 signalSum[rowIdx][colIdx+1][timeIdx] += PadResponse(dist+1.) * signal;
334 // Add the padcluster to the detector matrix
335 for (iRow = 0; iRow < rowBox; iRow++ ) {
336 for (Int_t iCol = 0; iCol < colBox; iCol++ ) {
337 for (Int_t iTime = 0; iTime < timeBox; iTime++) {
339 Int_t rowB = rowH + iRow - (Int_t) ( rowBox / 2);
340 Int_t colB = colH + iCol - (Int_t) ( colBox / 2);
341 Int_t timeB = timeH + iTime - (Int_t) (timeBox / 2);
343 Float_t signalB = signalSum[iRow][iCol][iTime];
345 matrix->AddSignal(rowB,colB,timeB,signalB);
346 if (!(matrix->AddTrack(rowB,colB,timeB,track)))
347 printf(" More than three tracks in a pixel!\n");
358 // Create the hits for this chamber
359 for (Int_t iRow = 0; iRow < fRowMax[iplan][icham][isect]; iRow++ ) {
360 for (Int_t iCol = 0; iCol < fColMax[iplan] ; iCol++ ) {
361 for (Int_t iTime = 0; iTime < fTimeMax ; iTime++) {
363 Float_t signalAmp = matrix->GetSignal(iRow,iCol,iTime);
366 signalAmp = TMath::Max(gRandom->Gaus(signalAmp,fNoise),(Float_t) 0.0);
370 signalAmp *= fChipGain;
371 // Convert to ADC counts
372 Int_t adc = (Int_t) (signalAmp * (fADCoutRange / fADCinRange));
374 // Apply threshold on ADC value
375 if (adc > fADCthreshold) {
378 for (Int_t ii = 0; ii < 3; ii++) {
379 trackSave[ii] = matrix->GetTrack(iRow,iCol,iTime,ii);
383 digits[0] = matrix->GetSector();
384 digits[1] = matrix->GetChamber();
385 digits[2] = matrix->GetPlane();
391 // Add this digit to the TClonesArray
392 AddDigit(trackSave,digits);
401 printf("AliTRDv1::Hits2Digits -- Number of digits found: %d\n",nDigits);
410 // Fill the digits-tree
411 printf("AliTRDv1::Hits2Digits -- Fill the digits tree\n");
416 //_____________________________________________________________________________
417 void AliTRDv1::Digits2Clusters()
421 // Method to convert AliTRDdigits created by AliTRDv1::Hits2Digits()
422 // into AliTRDclusters
423 // To produce cluster from a root-file with TRD-digits use the
424 // slowClusterCreate.C macro.
429 printf("AliTRDv1::Digits2Clusters -- Start creating clusters\n");
431 AliTRDdigit *TRDdigit;
432 TClonesArray *TRDDigits;
435 Float_t maxThresh = fClusMaxThresh; // threshold value for maximum
436 Float_t signalThresh = fClusSigThresh; // threshold value for digit signal
437 Int_t clusteringMethod = fClusMethod; // clustering method option (for testing)
439 const Float_t epsilon = 0.01; // iteration limit for unfolding procedure
441 // Get the pointer to the digits tree
442 TTree *DigitTree = gAlice->TreeD();
443 // Get the pointer to the cluster tree
444 TTree *ClusterTree = gAlice->TreeD();
446 // Get the pointer to the digits container
447 TRDDigits = Digits();
450 Int_t chamEnd = kNcham;
451 if (fSensChamber) chamEnd = chamBeg = fSensChamber;
453 Int_t planEnd = kNplan;
454 if (fSensPlane) planEnd = planBeg = fSensPlane;
456 Int_t sectEnd = kNsect;
457 if (fSensSector) sectEnd = sectBeg = fSensSector;
459 // Import the digit tree
460 gAlice->ResetDigits();
462 nbytes += DigitTree->GetEvent(1);
464 // Get the number of digits in the detector
465 Int_t nTRDDigits = TRDDigits->GetEntriesFast();
467 // *** Start clustering *** in every chamber
468 for (Int_t icham = chamBeg; icham < chamEnd; icham++) {
469 for (Int_t iplan = planBeg; iplan < planEnd; iplan++) {
470 for (Int_t isect = sectBeg; isect < sectEnd; isect++) {
473 printf("AliTRDv1::Digits2Clusters -- Finding clusters in chamber %d, plane %d, sector %d\n"
474 ,icham+1,iplan+1,isect+1);
476 // Create a detector matrix to keep maxima
477 AliTRDmatrix *digitMatrix = new AliTRDmatrix(fRowMax[iplan][icham][isect]
481 // Create a matrix to contain maximum flags
482 AliTRDmatrix *maximaMatrix = new AliTRDmatrix(fRowMax[iplan][icham][isect]
485 ,isect+1,icham+1,iplan+1);
487 // Loop through all TRD digits
488 for (Int_t iTRDDigits = 0; iTRDDigits < nTRDDigits; iTRDDigits++) {
490 // Get the information for this digit
491 TRDdigit = (AliTRDdigit*) TRDDigits->UncheckedAt(iTRDDigits);
492 Int_t signal = TRDdigit->fSignal;
493 Int_t sector = TRDdigit->fSector;
494 Int_t chamber = TRDdigit->fChamber;
495 Int_t plane = TRDdigit->fPlane;
496 Int_t row = TRDdigit->fRow;
497 Int_t col = TRDdigit->fCol;
498 Int_t time = TRDdigit->fTime;
501 for (Int_t iTrack = 0; iTrack < 3; iTrack++) {
502 track[iTrack] = TRDdigit->AliDigit::fTracks[iTrack];
505 if ((sector != isect+1) ||
506 (plane != iplan+1) ||
507 (chamber != icham+1))
510 // Fill the detector matrix
511 if (signal > signalThresh) {
512 digitMatrix->SetSignal(row,col,time,signal);
513 for (Int_t iTrack = 0; iTrack < 3; iTrack++) {
514 if (track[iTrack] > 0) {
515 digitMatrix->AddTrack(row,col,time,track[iTrack]);
522 // Loop chamber and find maxima in digitMatrix
523 for (row = 0; row < fRowMax[iplan][icham][isect]; row++) {
524 for (Int_t col = 1; col < fColMax[iplan] ; col++) {
525 for (Int_t time = 0; time < fTimeMax ; time++) {
527 if (digitMatrix->GetSignal(row,col,time)
528 < digitMatrix->GetSignal(row,col - 1,time)) {
531 if (digitMatrix->GetSignal(row,col - 2,time)
532 < digitMatrix->GetSignal(row,col - 1,time)) {
533 // yes, so set maximum flag
534 maximaMatrix->SetSignal(row,col - 1,time,1);
536 else maximaMatrix->SetSignal(row,col - 1,time,0);
544 // now check maxima and calculate cluster position
545 for (row = 0; row < fRowMax[iplan][icham][isect]; row++) {
546 for (Int_t col = 1; col < fColMax[iplan] ; col++) {
547 for (Int_t time = 0; time < fTimeMax ; time++) {
549 if ((maximaMatrix->GetSignal(row,col,time) > 0)
550 && (digitMatrix->GetSignal(row,col,time) > maxThresh)) {
552 Int_t clusters[5] = {0}; // cluster-object data
554 Float_t ratio = 0; // ratio resulting from unfolding
555 Float_t padSignal[5] = {0}; // signals on max and neighbouring pads
556 Float_t clusterSignal[3] = {0}; // signals from cluster
557 Float_t clusterPos[3] = {0}; // cluster in ALICE refFrame coords
558 Float_t clusterPads[6] = {0}; // cluster pad info
561 clusters[0] = isect+1; // = isect ????
562 clusters[1] = icham+1; // = ichamber ????
563 clusters[2] = iplan+1; // = iplane ????
566 clusterPads[0] = icham+1;
567 clusterPads[1] = isect+1;
568 clusterPads[2] = iplan+1;
570 for (Int_t iPad = 0; iPad < 3; iPad++) {
571 clusterSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
574 // neighbouring maximum on right side?
575 if (col < fColMax[iplan] - 2) {
576 if (maximaMatrix->GetSignal(row,col + 2,time) > 0) {
577 for (Int_t iPad = 0; iPad < 5; iPad++) {
578 padSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
582 ratio = Unfold(epsilon, padSignal);
584 // set signal on overlapping pad to ratio
585 clusterSignal[2] *= ratio;
589 switch (clusteringMethod) {
591 // method 1: simply center of mass
592 clusterPads[3] = row + 0.5;
593 clusterPads[4] = col - 0.5 + (clusterSignal[2] - clusterSignal[0]) /
594 (clusterSignal[1] + clusterSignal[2] + clusterSignal[3]);
595 clusterPads[5] = time + 0.5;
600 // method 2: integral gauss fit on 3 pads
601 TH1F *hPadCharges = new TH1F("hPadCharges", "Charges on center 3 pads"
603 for (Int_t iCol = -1; iCol <= 3; iCol++) {
604 if (clusterSignal[iCol] < 1) clusterSignal[iCol] = 1;
605 hPadCharges->Fill(iCol, clusterSignal[iCol]);
607 hPadCharges->Fit("gaus", "IQ", "SAME", -0.5, 2.5);
608 TF1 *fPadChargeFit = hPadCharges->GetFunction("gaus");
609 Double_t colMean = fPadChargeFit->GetParameter(1);
611 clusterPads[3] = row + 0.5;
612 clusterPads[4] = col - 1.5 + colMean;
613 clusterPads[5] = time + 0.5;
621 Float_t clusterCharge = clusterSignal[0]
624 clusters[4] = (Int_t)clusterCharge;
627 for (Int_t iTrack = 0; iTrack < 3; iTrack++) {
628 trackSave[iTrack] = digitMatrix->GetTrack(row,col,time,iTrack);
631 // Calculate cluster position in ALICE refFrame coords
632 // and set array clusterPos to calculated values
633 Pads2XYZ(clusterPads, clusterPos);
635 // Add cluster to reconstruction tree
636 AddCluster(trackSave,clusters,clusterPos);
644 printf("AliTRDv1::Digits2Clusters -- Number of clusters found: %d\n",nClusters);
653 // Fill the cluster-tree
654 printf("AliTRDv1::Digits2Clusters -- Total number of clusters found: %d\n"
655 ,fClusters->GetEntries());
656 printf("AliTRDv1::Digits2Clusters -- Fill the cluster tree\n");
661 //_____________________________________________________________________________
662 void AliTRDv1::Init()
665 // Initialise Transition Radiation Detector after geometry has been built.
666 // Includes the default settings of all parameter for the digitization.
671 printf(" Slow simulator\n");
673 printf(" Only plane %d is sensitive\n",fSensPlane);
675 printf(" Only chamber %d is sensitive\n",fSensChamber);
677 printf(" Only sector %d is sensitive\n",fSensSector);
679 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
680 const Float_t kPoti = 12.1;
681 // Maximum energy (50 keV);
682 const Float_t kEend = 50000.0;
683 // Ermilova distribution for the delta-ray spectrum
684 Float_t Poti = TMath::Log(kPoti);
685 Float_t Eend = TMath::Log(kEend);
686 fDeltaE = new TF1("deltae",Ermilova,Poti,Eend,0);
688 // Identifier of the sensitive volume (drift region)
689 fIdSens = gMC->VolId("UL05");
691 // Identifier of the TRD-driftchambers
692 fIdChamber1 = gMC->VolId("UCIO");
693 fIdChamber2 = gMC->VolId("UCIM");
694 fIdChamber3 = gMC->VolId("UCII");
696 // The default parameter for the digitization
697 if (!(fGasGain)) fGasGain = 2.0E3;
698 if (!(fNoise)) fNoise = 3000.;
699 if (!(fChipGain)) fChipGain = 10.;
700 if (!(fADCoutRange)) fADCoutRange = 255.;
701 if (!(fADCinRange)) fADCinRange = 2000.;
702 if (!(fADCthreshold)) fADCthreshold = 1;
704 // Transverse and longitudinal diffusion coefficients (Xe/Isobutane)
705 if (!(fDiffusionT)) fDiffusionT = 0.060;
706 if (!(fDiffusionL)) fDiffusionL = 0.017;
708 // The default parameter for the clustering
709 if (!(fClusMaxThresh)) fClusMaxThresh = 5.0;
710 if (!(fClusSigThresh)) fClusSigThresh = 2.0;
711 if (!(fClusMethod)) fClusMethod = 1;
713 for (Int_t i = 0; i < 80; i++) printf("*");
718 //_____________________________________________________________________________
719 Float_t AliTRDv1::PadResponse(Float_t x)
722 // The pad response for the chevron pads.
723 // We use a simple Gaussian approximation which should be good
724 // enough for our purpose.
727 // The parameters for the response function
728 const Float_t aa = 0.8872;
729 const Float_t bb = -0.00573;
730 const Float_t cc = 0.454;
731 const Float_t cc2 = cc*cc;
733 Float_t pr = aa * (bb + TMath::Exp(-x*x / (2. * cc2)));
739 //_____________________________________________________________________________
740 void AliTRDv1::SetSensPlane(Int_t iplane)
743 // Defines the hit-sensitive plane (1-6)
746 if ((iplane < 0) || (iplane > 6)) {
747 printf("Wrong input value: %d\n",iplane);
748 printf("Use standard setting\n");
759 //_____________________________________________________________________________
760 void AliTRDv1::SetSensChamber(Int_t ichamber)
763 // Defines the hit-sensitive chamber (1-5)
766 if ((ichamber < 0) || (ichamber > 5)) {
767 printf("Wrong input value: %d\n",ichamber);
768 printf("Use standard setting\n");
775 fSensChamber = ichamber;
779 //_____________________________________________________________________________
780 void AliTRDv1::SetSensSector(Int_t isector)
783 // Defines the hit-sensitive sector (1-18)
786 if ((isector < 0) || (isector > 18)) {
787 printf("Wrong input value: %d\n",isector);
788 printf("Use standard setting\n");
795 fSensSector = isector;
799 //_____________________________________________________________________________
800 void AliTRDv1::StepManager()
803 // Called at every step in the Transition Radiation Detector version 2.
804 // Slow simulator. Every charged track produces electron cluster as hits
805 // along its path across the drift volume. The step size is set acording
806 // to Bethe-Bloch. The energy distribution of the delta electrons follows
807 // a spectrum taken from Ermilova et al.
810 Int_t iIdSens, icSens;
811 Int_t iIdSpace, icSpace;
812 Int_t iIdChamber, icChamber;
824 Double_t betaGamma, pp;
826 TLorentzVector pos, mom;
827 TClonesArray &lhits = *fHits;
829 const Double_t kBig = 1.0E+12;
832 const Float_t kWion = 22.04;
833 // Maximum energy for e+ e- g for the step-size calculation
834 const Float_t kPTotMax = 0.002;
835 // Plateau value of the energy-loss for electron in xenon
836 // taken from: Allison + Comb, Ann. Rev. Nucl. Sci. (1980), 30, 253
837 //const Double_t kPlateau = 1.70;
838 // the averaged value (26/3/99)
839 const Float_t kPlateau = 1.55;
840 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
841 const Float_t kPrim = 48.0;
842 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
843 const Float_t kPoti = 12.1;
845 // Set the maximum step size to a very large number for all
846 // neutral particles and those outside the driftvolume
847 gMC->SetMaxStep(kBig);
849 // Use only charged tracks
850 if (( gMC->TrackCharge() ) &&
851 (!gMC->IsTrackStop() ) &&
852 (!gMC->IsTrackDisappeared())) {
854 // Inside a sensitive volume?
855 iIdSens = gMC->CurrentVolID(icSens);
856 if (iIdSens == fIdSens) {
858 iIdSpace = gMC->CurrentVolOffID(4,icSpace );
859 iIdChamber = gMC->CurrentVolOffID(1,icChamber);
861 // Calculate the energy of the delta-electrons
862 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
863 eDelta = TMath::Max(eDelta,0.0);
865 // The number of secondary electrons created
866 qTot = (Double_t) ((Int_t) (eDelta / kWion) + 1);
868 // The hit coordinates and charge
869 gMC->TrackPosition(pos);
876 Float_t phi = pos[1] != 0 ? TMath::Atan2(pos[0],pos[1]) : (pos[0] > 0 ? 180. : 0.);
877 vol[0] = ((Int_t) (phi / 20)) + 1;
879 // The chamber number
885 if (iIdChamber == fIdChamber1)
886 vol[1] = (hits[2] < 0 ? 1 : 5);
887 else if (iIdChamber == fIdChamber2)
888 vol[1] = (hits[2] < 0 ? 2 : 4);
889 else if (iIdChamber == fIdChamber3)
893 vol[2] = icChamber - TMath::Nint((Float_t) (icChamber / 7)) * 6;
895 // Check on selected volumes
896 Int_t addthishit = 1;
898 if ((fSensPlane) && (vol[2] != fSensPlane )) addthishit = 0;
899 if ((fSensChamber) && (vol[1] != fSensChamber)) addthishit = 0;
900 if ((fSensSector) && (vol[0] != fSensSector )) addthishit = 0;
906 new(lhits[fNhits++]) AliTRDhit(fIshunt,gAlice->CurrentTrack(),vol,hits);
908 // The energy loss according to Bethe Bloch
909 gMC->TrackMomentum(mom);
911 iPid = gMC->TrackPid();
913 ((iPid <= 3) && (pTot < kPTotMax))) {
914 aMass = gMC->TrackMass();
915 betaGamma = pTot / aMass;
916 pp = kPrim * BetheBloch(betaGamma);
917 // Take charge > 1 into account
918 charge = gMC->TrackCharge();
919 if (TMath::Abs(charge) > 1) pp = pp * charge*charge;
921 // Electrons above 20 Mev/c are at the plateau
923 pp = kPrim * kPlateau;
926 // Calculate the maximum step size for the next tracking step
930 while ((random[0] == 1.) || (random[0] == 0.));
931 gMC->SetMaxStep( - TMath::Log(random[0]) / pp);
936 // set step size to maximal value
937 gMC->SetMaxStep(kBig);
946 //_____________________________________________________________________________
947 Double_t AliTRDv1::BetheBloch(Double_t bg)
950 // Parametrization of the Bethe-Bloch-curve
951 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
954 // This parameters have been adjusted to averaged values from GEANT
955 const Double_t kP1 = 7.17960e-02;
956 const Double_t kP2 = 8.54196;
957 const Double_t kP3 = 1.38065e-06;
958 const Double_t kP4 = 5.30972;
959 const Double_t kP5 = 2.83798;
961 // This parameters have been adjusted to Xe-data found in:
962 // Allison & Cobb, Ann. Rev. Nucl. Sci. (1980), 30, 253
963 //const Double_t kP1 = 0.76176E-1;
964 //const Double_t kP2 = 10.632;
965 //const Double_t kP3 = 3.17983E-6;
966 //const Double_t kP4 = 1.8631;
967 //const Double_t kP5 = 1.9479;
970 Double_t yy = bg / TMath::Sqrt(1. + bg*bg);
971 Double_t aa = TMath::Power(yy,kP4);
972 Double_t bb = TMath::Power((1./bg),kP5);
973 bb = TMath::Log(kP3 + bb);
974 return ((kP2 - aa - bb)*kP1 / aa);
981 //_____________________________________________________________________________
982 Double_t Ermilova(Double_t *x, Double_t *)
985 // Calculates the delta-ray energy distribution according to Ermilova.
986 // Logarithmic scale !
997 Float_t vxe[nV] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
998 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
999 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1000 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1001 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1002 , 9.4727, 9.9035,10.3735,10.5966,10.8198
1005 Float_t vye[nV] = { 80.0 , 31.0 , 23.3 , 21.1 , 21.0
1006 , 20.9 , 20.8 , 20.0 , 16.0 , 11.0
1007 , 8.0 , 6.0 , 5.2 , 4.6 , 4.0
1008 , 3.5 , 3.0 , 1.4 , 0.67 , 0.44
1009 , 0.3 , 0.18 , 0.12 , 0.08 , 0.056
1010 , 0.04 , 0.023, 0.015, 0.011, 0.01
1015 // Find the position
1019 dpos = energy - vxe[pos2++];
1023 if (pos2 > nV) pos2 = nV;
1026 // Differentiate between the sampling points
1027 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1033 //_____________________________________________________________________________
1034 void AliTRDv1::Pads2XYZ(Float_t *pads, Float_t *pos)
1036 // Method to convert pad coordinates (row,col,time)
1037 // into ALICE reference frame coordinates (x,y,z)
1039 Int_t chamber = (Int_t) pads[0]; // chamber info (1-5)
1040 Int_t sector = (Int_t) pads[1]; // sector info (1-18)
1041 Int_t plane = (Int_t) pads[2]; // plane info (1-6)
1043 Int_t icham = chamber - 1; // chamber info (0-4)
1044 Int_t isect = sector - 1; // sector info (0-17)
1045 Int_t iplan = plane - 1; // plane info (0-5)
1047 Float_t padRow = pads[3]; // Pad Row position
1048 Float_t padCol = pads[4]; // Pad Column position
1049 Float_t timeSlice = pads[5]; // Time "position"
1051 // calculate (x,y) position in rotated chamber
1052 Float_t yRot = fCol0[iplan] + padCol * fColPadSize;
1053 Float_t xRot = fTime0[iplan] + timeSlice * fTimeBinSize;
1054 // calculate z-position:
1055 Float_t z = fRow0[iplan][icham][isect] + padRow * fRowPadSize;
1058 rotate chamber back to original position
1059 1. mirror at y-axis, 2. rotate back to position (-phi)
1060 / cos(phi) -sin(phi) \ / -1 0 \ / -cos(phi) -sin(phi) \
1061 \ sin(phi) cos(phi) / * \ 0 1 / = \ -sin(phi) cos(phi) /
1063 //Float_t phi = 2*kPI / kNsect * ((Float_t) sector - 0.5);
1064 //Float_t x = -xRot * TMath::Cos(phi) - yRot * TMath::Sin(phi);
1065 //Float_t y = -xRot * TMath::Sin(phi) + yRot * TMath::Cos(phi);
1066 Float_t phi = 2*kPI / kNsect * ((Float_t) sector - 0.5);
1067 Float_t x = -xRot * TMath::Cos(phi) + yRot * TMath::Sin(phi);
1068 Float_t y = xRot * TMath::Sin(phi) + yRot * TMath::Cos(phi);
1077 //_____________________________________________________________________________
1078 Float_t AliTRDv1::Unfold(Float_t eps, Float_t* padSignal)
1080 // Method to unfold neighbouring maxima.
1081 // The charge ratio on the overlapping pad is calculated
1082 // until there is no more change within the range given by eps.
1083 // The resulting ratio is then returned to the calling method.
1085 Int_t itStep = 0; // count iteration steps
1087 Float_t ratio = 0.5; // start value for ratio
1088 Float_t prevRatio = 0; // store previous ratio
1090 Float_t newLeftSignal[3] = {0}; // array to store left cluster signal
1091 Float_t newRightSignal[3] = {0}; // array to store right cluster signal
1094 while ((TMath::Abs(prevRatio - ratio) > eps) && (itStep < 10)) {
1099 // cluster position according to charge ratio
1100 Float_t maxLeft = (ratio*padSignal[2] - padSignal[0]) /
1101 (padSignal[0] + padSignal[1] + ratio*padSignal[2]);
1102 Float_t maxRight = (padSignal[4] - (1-ratio)*padSignal[2]) /
1103 ((1-ratio)*padSignal[2] + padSignal[3] + padSignal[4]);
1105 // set cluster charge ratio
1106 Float_t ampLeft = padSignal[1];
1107 Float_t ampRight = padSignal[3];
1109 // apply pad response to parameters
1110 newLeftSignal[0] = ampLeft*PadResponse(-1 - maxLeft);
1111 newLeftSignal[1] = ampLeft*PadResponse( 0 - maxLeft);
1112 newLeftSignal[2] = ampLeft*PadResponse( 1 - maxLeft);
1114 newRightSignal[0] = ampRight*PadResponse(-1 - maxRight);
1115 newRightSignal[1] = ampRight*PadResponse( 0 - maxRight);
1116 newRightSignal[2] = ampRight*PadResponse( 1 - maxRight);
1118 // calculate new overlapping ratio
1119 ratio = newLeftSignal[2]/(newLeftSignal[2] + newRightSignal[0]);